Q.stems of red twig dogwood
Our bush is about 15 years old and some of the stems have a scale on them. I am still getting some leaves but wondering if they will be healthy.

Basically, you are going to want to thoroughly spray the tree with horticultural oil, being sure to thoroughly coat all branches. Apply the oil before new growth begins and again after flowering.
For more information on scale, please review the following link:
https://www.gardeningknowhow.com/plant-problems/pests/insects/control-plant-scale.htm